/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.util;

import proguard.classfile.*;
import proguard.classfile.attribute.Attribute;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.visitor.ClassVisitor;

/**
 * This ClassVisitor shares strings in the class files that it visits.
 *
 * @author Eric Lafortune
 */
public class StringSharer extends SimplifiedVisitor implements ClassVisitor, ConstantVisitor, AttributeVisitor {
    // A fields acting as an argument for the visitor methods.
    private String name;
    private String type;

    // Implementations for ClassVisitor.

    public void visitProgramClass(ProgramClass programClass) {
        // Replace name strings in the constant pool by shared strings.
        programClass.constantPoolEntriesAccept(this);

        // Replace attribute name strings in the constant pool by internalized
        // strings.
        programClass.attributesAccept(this);
    }

    public void visitLibraryClass(LibraryClass libraryClass) {
        // Replace the super class name string by the shared name string.
        Clazz superClass = libraryClass.superClass;
        if (superClass != null) {
            libraryClass.superClassName = superClass.getName();
        }

        // Replace the interface name strings by the shared name strings.
        if (libraryClass.interfaceNames != null) {
            String[] interfaceNames = libraryClass.interfaceNames;
            Clazz[] interfaceClasses = new Clazz[interfaceNames.length];

            for (int index = 0; index < interfaceNames.length; index++) {
                // Keep a reference to the interface class.
                Clazz interfaceClass = interfaceClasses[index];
                if (interfaceClass != null) {
                    interfaceNames[index] = interfaceClass.getName();
                }
            }
        }
    }

    // Implementations for ConstantVisitor.

    public void visitAnyConstant(Clazz clazz, Constant constant) {}

    public void visitStringConstant(Clazz clazz, StringConstant stringConstant) {
        Member referencedMember = stringConstant.referencedMember;
        if (referencedMember != null) {
            Clazz referencedClass = stringConstant.referencedClass;

            // Put the actual class member's name in the class pool.
            name = referencedMember.getName(referencedClass);
            clazz.constantPoolEntryAccept(stringConstant.u2stringIndex, this);
        }
    }

    public void visitAnyRefConstant(Clazz clazz, RefConstant refConstant) {
        Member referencedMember = refConstant.referencedMember;
        if (referencedMember != null) {
            Clazz referencedClass = refConstant.referencedClass;

            // Put the actual class member's name and type strings in the class
            // pool.
            name = referencedMember.getName(referencedClass);
            type = referencedMember.getDescriptor(referencedClass);
            clazz.constantPoolEntryAccept(refConstant.u2nameAndTypeIndex, this);
        }
    }

    public void visitNameAndTypeConstant(Clazz clazz, NameAndTypeConstant nameAndTypeConstant) {
        if (name != null) {
            // Put the actual class member's name and type strings in the class
            // pool.
            clazz.constantPoolEntryAccept(nameAndTypeConstant.u2nameIndex, this);
            name = type;
            clazz.constantPoolEntryAccept(nameAndTypeConstant.u2descriptorIndex, this);
        }
    }

    public void visitClassConstant(Clazz clazz, ClassConstant classConstant) {
        Clazz referencedClass = classConstant.referencedClass;
        if (referencedClass != null) {
            // Put the actual class's name string in the class pool.
            name = referencedClass.getName();
            clazz.constantPoolEntryAccept(classConstant.u2nameIndex, this);
        }
    }

    public void visitUtf8Constant(Clazz clazz, Utf8Constant utf8Constant) {
        // Do we have a new string to put into this constant?
        if (name != null) {
            // Replace the string, if it's actually the same.
            if (name.equals(utf8Constant.getString())) {
                utf8Constant.setString(name);
            }

            name = null;
        }
    }

    // Implementations for AttributeVisitor.

    public void visitAnyAttribute(Clazz clazz, Attribute attribute) {
        // Put the internalized attribute's name string in the class pool.
        name = attribute.getAttributeName(clazz).intern();
        clazz.constantPoolEntryAccept(attribute.u2attributeNameIndex, this);
    }
}
